8.4 Sustainable management of coasts Flashcards
Coastal management definition
Any technique used to purposefully solve/reduce pressures faced along a coastline. Includes hard & soft engineering solutions (coastal protection/defence against erosion & flooding), but broader eg sustainable management
Sustainable management
Social, economic + environmental sustainable development
Strategies must work in the present + the future
Assessment criteria for sustainable management
GOOD if:
- Long-term (not short-term)
- Needs to be sustainable in order to safeguard the use of the coastal zone for future generations
- Not much maintenance or repair required
- Tailored to local conditions / issues: i.e. a detailed knowledge of coastal processes in that sediment cell. Takes into account effect on areas downdrift e.g. positive feedback loops such as assessing if reduced LSD creates detrimental effects downdrift of the management strategy
- Economic benefits: management is cheap to build/do & maintain (costs match benefits); protects key economic assets in area (eg. buildings, roads, infrastructure); land values maintained; standard of living in coastal communities maintained or improved (fishing; tourism opportunities)
- Social benefits – e.g. improving Quality Of Life of coastal communities; recreational value + accessibility; creation of beach; visually attractive; peace of mind for residents (not making them homeless); employment perhaps?
- Environmental benefits – e.g. no disruption to ecosystems and habitats (conservation of these); no disruption to natural coastal processes; prevention of pollution; maintaining aesthetic appeal of coastline
Cost Benefit Analaysis: Benefits outweigh the costs. BUT difficult to measure soc/env costs and benefits
Social, economic, environmental considerations need to be weighed up against each other
FINISH WITH IDEA THAT SUSTAINABLE MANAGEMENT IS COMPLEX & DIFFICULT TO ACHIEVE.
‘Sea’ may win in end (delaying the inevitable). Management may also create problems in other places thereby requiring expensive intervention. Humans’ intervention in natural coastal processes may NEVER be sustainable in long-term??? Questions to ask….
* Will it stop/reduce erosion? - 70% of UK’s sandy coastlines are eroding and sea levels are rising – predicted by 2029 that 2000 residential properties and 15km of transport lines may be vulnerable to coastal erosion.
* What is impact on other areas of coast?
* Will it protect against rising sea levels?
* Is it appropriate? (Environmental Impact Assessment)
* Does it affect natural beauty of coastline?
* Is it cost effective? (CBA)
* Is land or property lost?
* What would public perception be?
* How feasible is it? (engineering & coastal system perspective?
Management approach in the UK
Shoreline Management Plan (SMP)
Plans in England & Wales designed to develop sustainable coastal defence schemes. Sections of the coast are divided up into littoral (sediment) cells (and within these cells there are many sub-cells defined by sediment movement) and plans are drawn up for the use and protection of each zone. Risk assessments are drawn up associated with coastal erosion and flooding. They provide management plans for the short term (20 years), medium term (20-50years) and long term (50-100
years) and makes sure that management is sustainable with other wider, strategic plans. Holistic approach is used: any future management strategy considered in context of whole sediment cell.
4 coastal defence options within a SMP
- Do Nothing
- Hold the Line (maintain existing levels of defence)
- Retreat the Line or ‘managed realignment’ (allow retreat of coast)
- Advance the Line (building new defences on seaward side)
Integrated Coastal Zone Management (ICZM)
Management which takes into consideration the whole range of activities that take place in the coastal zone, in order to reduce potential conflict between stakeholders. A holistic approach, taking all physical and human factors into account. Management strategy must be considered in the context of the whole sediment cell.
Do Nothing + eval
No further investment in coastal defence. Popular with taxpayer but unpopular with local people who will lose farms, houses or businesses in the near future Viable only if the coastline in question is undeveloped and nothing is at stake by giving up land to coastal erosion EG Cuckmere Haven, East Sussex Helps maintain dynamic nature of the coastline – allows it to adjust to rising sea levels naturally. Beneficial to allow as many areas as possible to retreat naturally because erosion of these areas liberates sediment which may lessen the impact of sea-level rise on those areas that are not allowed to retreat naturally. The outcome is an increase in resilience of the coastline to cope with rising sea levels so from geomorphological point of view, this is the most sustainable though not from a socio-economic point of view
Hold the line + Eval
Maintain and repairing the current hard coastal defences so that the coastline is protected from further coastal erosion and so the risk of future coastal flooding is not increased. May also be through soft engineering like beach nourishment Considered to be increasingly expensive at a time when sea levels are rising and more coastal storms predicted. However, usually the minimum that coastal communities will accept! Protects economic assets and politically popular. Only economically justifiable if the land to be protected is of great value
Advance the line + Eval
Building new defences on the seaward side of the original defences. May involve reclaiming land from the sea. Very expensive especially with impacts of climate change Rarely applied but occurs when large amounts of sediment are applied eg Sand Engine in Netherlands. Increases resilience of the coastline to erosion with its buffering capacity. Land reclamation in Singapore and Hong Kong further egs.
Managed realignment + Eval
Allowing the shoreline to move backwards or forwards but with the use of management strategies that will control this movement. In the UK this usually involves managed retreat, involving relocation of coastal communities and industry with prohibition on further development. Risks are minimised and costs of protection are avoided. However, social and economic costs of relocation and compensation are potentially high. Requires strong government with powerful legislation Helps maintain dynamic nature of the coastline – allows it to adjust to rising sea levels naturally. Beneficial to allow as many areas as possible to retreat naturally because erosion of these areas liberates sediment which may lessen the impact of sea-level rise on those areas that are not allowed to retreat naturally. The outcome is an increase in resilience of the coastline to cope with rising sea levels so from geomorphological point of view, this is the most sustainable though not from a socio-economic point of view EG Humber Estuary
Should management prioritise hard or soft engineering?
Hard Engineering – controlling nature – artificial structures to reflect or absorb wave energy eg sea walls, groynes, rip rap, gabions and revetments
When designed properly, hard engineering structures serve an important purpose; storm surge barriers eg Thames Barreir have prevented serious flooding, sea walls control coastal damage during extreme wave events and groynes are successful to some extent in trapping sediments and maintaining a beach to absorb wave energy.
Side effects of hard engineering are considerable – agreed that construction of hard engineering create erosion problems ude to positive feedback loops on the down-drift unprotected coastline or even exacerbated (terminal groyne syndrom and terminal scour)
Soft Engineering – working with nature to protect the coastline by enhancing the natural and protective coastal processes eg beach nourishment, sand dune conservation and regeneration, managed retreat, cliff drainage and cliff re-grading. Soft engineering strategies are becoming more popular as they work with the coast’s natural, protective processes.
Beach nourishment largely circumvents the problems associated with hard engineering outlined above. The artificial placement of sediment either on the underwater slope or on the beach itself protects not only the recharged coast but also the neighbouring coastline because marine transport will redistribute the nourished sediment.
However this is a major downside of beach nourishment – it will have to be repeated at regular intervals at large cumulative costs. To reduce the sediment loss, groynes may be placed at the boundaries of the nourished area.
On the whole, beach nourishment is more aligned with sustainable coastal management
